The objective of this project is to develop antibodies specific for human immunodeficiency virus (HIV) that can be used in a vaginal microbicide for preventing sexual transmission of HIV. These HIV antibodies can be combined with antibodies against other sexually transmitted disease pathogens already being produced in corn (plantibodies) by Epicyte for broad-spectrum vaginal protection. Human monoclonal antibodies 2F5 (anti-gp4l) and 2G12 (anti-gpl20) are widely recognized as two of the most potent and broadly neutralizing HIV antibodies developed to date, and have been shown to prevent vaginal transmission of SHIV in macaques when administered systemically. 2F5 and 2G12 will be produced as secretory IgAs (SIgA), the isotype most predominant on mucosal surfaces. The antibody genes will be introduced into corn plants and expressed in seeds as "plantibodies" for low cost and large capacity production. Antibodies will be purified from seeds, combined in a single formulation, and evaluated for effectiveness in preventing vaginal transmission of SHIV in macaques when applied topically to the vagina. The results from phase I funding will provide essential information and GMP material to support clinical trials in the second phase of this SBIR proposal. PROPOSED COMMERCIAL APPLICATION: Plantibodies offer a unique opportunity to provide large quantities of protective antibodies at a cost that enables technology that prevents mucosal transmission of a wide range of infectious diseases.